JP2707578B2 - Charge display device for vehicle voltage regulator - Google Patents

Description

The present invention relates to a charging device for an automobile or the like, and to a charging display device for a voltage regulator thereof.

2. Description of the Related Art A charge display device is a device that turns on a charge indicator light (charge lamp) to warn a driver after a key switch is turned on and before a generator starts generating power. In some voltage regulators (regulators) provided with this type of charge display device, the turning on of a key switch is detected by a drive terminal (L terminal) of a charge lamp to reduce wiring.

 FIG. 6 is a circuit diagram showing a conventional device.

A key switch 2, a charge lamp 3, a lamp driving transistor 5, and a diode 6 are connected in series from the positive electrode to the negative electrode of the battery 1, and a circuit is formed in which the charge lamp 3 is turned on by the conduction of the lamp driving transistor 5. ing. The L terminal 4 which is a connection point between the charge lamp 3 and the lamp driving transistor 5 is connected to the base of the closing detection transistor 9 via the resistors 7 and 8, and the conduction of the closing detection transistor 9 turns on the PNP transistor 10. The circuit is in a state where a base current is supplied to the lamp driving transistor 5 and the excitation transistor 12 in the excitation current control circuit 11 to make it conductive. Zener diode
Reference numeral 13 denotes a charging voltage adjusting member, which is turned on when the battery voltage exceeds the adjusted voltage, turns on the transistor 14, and turns on the PN.
The current from the P transistor 10 is bypassed, and the exciting transistor 12 is cut off. Rotor coil 17 of generator 16
The diode 15 connected in parallel with the (field coil) is a flywheel diode. The generator 16 includes a three-phase armature winding 18, a rotor coil 17 and a full-wave rectifier 19.

A light-off transistor 21 is connected to the base of the lamp driving transistor 5 for driving the charge lamp 3. The light-off transistor 21 is driven by a circuit (not shown) that detects the voltage of the armature winding 18 of the generator 16,
The circuit is turned on when the voltage of the armature winding 18 rises, and the current from the PNP transistor 10 is bypassed to cut off the lamp driving transistor 5.

[Problem to be Solved by the Invention] In the conventional device, a diode 6 is inserted in series with a lamp driving transistor 5. This is because when the charge lamp 3 is turned on, the voltage of the L terminal 4 becomes low, and the operation of the closing detection transistor 9 becomes unstable only with the voltage between the collector and the emitter of the lamp driving transistor 5, so that the level shift is attempted. is there.

However, the insertion of the diode 6, which is a power element, causes an increase in heat generation, an increase in mounting space, and a problem of an increase in cost. There is also a problem that it is difficult to make an IC.

Further, in the conventional device, the turning on of the key switch 2 is substantially detected by the base current flowing into the turning-on detection transistor 9. The base current value that makes the transistor conductive is greatly affected by temperature and becomes extremely small at high temperatures. For this reason, at high temperatures, even when the key switch 2 is open, there is a problem that the voltage regulator may malfunction due to a small leak current flowing into the L terminal 4. There are many problems that the voltage regulator is used under a high temperature environment from its mounting position.

The present invention has been made to solve the above-mentioned problems, and does not require the insertion of the diode 6 as a power element, and aims to reduce the mounting space as a circuit configuration that can be easily integrated into an IC. It is an object of the present invention to provide a charge display device of a voltage regulator for a vehicle, which does not easily malfunction due to a leak current to a terminal 4.

Means for Solving the Problems To achieve the above object, in the present invention, a circuit in which a key switch, a charge indicator light, and a transistor are connected in series from the positive electrode to the negative electrode of the battery is provided. In addition to having a function of lighting the charge indicator light by conduction, a connection point between the charge indicator light and the transistor (hereinafter referred to as L
Terminal), the charging display device of the vehicular voltage regulator that detects the turning on of the key switch based on the voltage of the key switch and excites the generator.
A setting voltage application circuit for respectively providing a set voltage of the first and second sets, a closing detection circuit for detecting the voltage of the L terminal and outputting a detection signal when the voltage exceeds the first set voltage, and exciting the generator based on the detection signal And a base current control circuit capable of detecting the voltage of the L terminal and supplying a base current that is increased or decreased according to a difference from the second set voltage to the transistor. And a charge display device for a voltage regulator for a vehicle.

[Operation] In the device configured as described above, when the key switch is turned on, if the voltage at the L terminal is lower than the second set voltage, the base current to the transistor is reduced, and the voltage between the collector and the emitter of the transistor is increased. . For this reason, even when the charging indicator lamp is turned on, the voltage of the L terminal is maintained at a voltage close to or higher than the second set voltage and is maintained at a voltage higher than the first set voltage. Detect input.

"Example" An example of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a device according to an embodiment. Since the generator 16 and the exciting current control circuit 11 are the same as those of the conventional apparatus shown in FIG. 6, the same reference numerals are given and the description is omitted.

A lamp driving transistor 5 is connected in series from a positive electrode of the battery 1 via a key switch 2, a charge lamp 3, and an L terminal 4 to form a circuit extending to a negative electrode (ground line 31) of the battery. Unlike the conventional device, the diode 6 for level shift is not inserted. A resistor connected in parallel with the lamp driving transistor 5 between the L terminal 4 and the ground line 31 is a leak compensation resistor 32.

The L terminal 4 is connected to a negative terminal of a closing detection circuit 33 composed of a comparator and a positive terminal of a base current control circuit 34 composed of a differential amplifier, respectively. In addition, a voltage dividing circuit including three resistors 36, 37, and 38 is provided between the power supply line 35 connected to the positive electrode of the battery 1 and the ground line 31. The first connection point 41 supplies a relatively low first set voltage V ₁ and is connected to the positive terminal of the closing detection circuit 33. Second connection point 42
It is connected to the negative terminal of the first set given higher second set voltage V ₂ than the voltage V _1, the base current control circuit 34. The voltage dividing circuit including the three resistors 36, 37, and 38 constitutes a setting voltage applying circuit.

The output of the closing detection circuit 33 is connected to the base of the PNP transistor 10. The PNP transistor 10 is an element that switches between the power supply line 35 and the control power supply line 43, and supplies a current to the excitation current control circuit 11 and the base current control circuit 34 according to the output of the closing detection circuit 33.

The output of the base current control circuit 34 is connected to the base of the lamp driving transistor 5. A light-off transistor 21 is connected to the same output, and is turned on by a circuit (not shown) for detecting the voltage of the armature winding 18, so that the lamp driving transistor 5 is turned off and the charge lamp 3 is turned off during charging. ing.

FIG. 2 is a circuit diagram showing the base current control circuit 34.
In this control circuit, the input stage is configured by a differential amplifier circuit including a constant current circuit 51 and a PNP transistor 52, and the output stage is configured by a resistor 53 and an NPN transistor 54. One of the inputs is connected to a junction 42 providing a _second set voltage V2,
The other input is connected to L terminal 4. The power input is connected to the control power line 43. In the present embodiment, since a differential amplifier circuit is used for the base current control circuit 34, high-precision control is possible.

 The operation based on the above configuration will be described.

If the key switch 2 is open, the voltage V _L of the L terminal 4 the output of OV, and the first set voltages V ₁ lower order than on detecting circuit 33 becomes high level to turn off the PNP transistor 10 . Therefore, the base current is not supplied to the excitation transistor 12, the transistor 12 is turned off, and the rotor coil 17 is not excited.
At this time, even if a small leak current flows into the L terminal 4, the rise in the voltage of the L terminal 4 is relatively small because the current flows through the leak compensation resistor 33, and the first voltage established by the voltage dividing resistors 36, 37, and 38. may exceed the set voltage V ₁ is not.

When the key switch 2 is turned on the voltage V _L of the L terminal 4 is increased. The voltage V _L of the L terminal 4 is at least the first set voltage
The output of the ON detection circuit 33 exceeds V ₁ is changed to the low level, the PNP transistor 10 conductive. As a result,
The voltage V is applied to the exciting current control circuit 11 and the base current control circuit 34.
_CC is supplied, and both circuits 11, 34 start operating. In the excitation current control circuit 11, the excitation transistor 12 is turned on, and the excitation of the rotor coil 17 is started.

In the base current control circuit 34, a base current is supplied to the lamp driving transistor 5, and the transistor 5 is turned on to turn on the charge lamp 3. Is conducting the lamp driving transistor 5, the voltage V _L of the L terminal 4 is to the base current suppressing decrease tries to increase the voltage V _L of the L terminal 4. That is, since the base current control circuit 34 is a differential amplifier, the L terminal voltage _VL is controlled to a voltage near the _second set voltage V2 as a reference for comparison. Therefore, the voltage V _L of the L terminal 4 after the key switch 2 is turned on, on detecting circuit 33
Detection voltage first specified voltage will be held at a voltage higher than V ₁ is, it is possible to detect reliably the key switch 2 is turned of.

Here, the minimum current of the L terminal 4 when the PNP transistor 10 is turned on will be compared with the conventional device shown in FIG. In the conventional device, _assuming that the voltage between the base and the emitter of the on-state detection transistor 9 is V _BE9 and the resistance value of the resistor 8 is R ₈ , the L terminal current I _L ′ is I _L ′ = V _BE9 / R ₈ . On the other hand, in the device of the present invention, the resistance value of the leak compensation resistor 32 is
As R ₃₂ , I _L = V ₁ / R ₃₂ (2) Generally, the base-emitter voltage V of a transistor
_{Since BE} has a large temperature dependence, the L terminal current I _L ′ required to turn on the PNP transistor 10 decreases in a conventional device at a high temperature, and a malfunction may occur due to a slight leak current. In contrast, in this embodiment apparatus, the first set voltages V ₁ also Sadamari in division ratio of the resistors 36, 37, 38, L terminal current I _L has little temperature characteristics. Therefore, a stable operation can be performed without a risk of malfunction even in a high-temperature environment.

Next, L necessary to make the PNP transistor 10 conductive is
Consider a difference voltage ΔV _L between the terminal voltage V _L0 and the L terminal voltage V _L1 in a steady state after the key switch 2 is turned on. The greater the difference voltage ΔV _L = V _L1 −V _L0 , the more reliably and more stably the key switch 2 can be detected from the L terminal 4. In the conventional device, the resistance values of the resistors ₇ and ₈ are R ₇ and R ₈ , the collector-emitter voltage (saturation voltage) of the lamp driving transistor 5 is V _CE5 , and the forward voltage drop of the diode 6 is V _d6 . V _L0 = V _BE9 × (1 + R ₇ / R ₈ ) (3) V _L1 = V _CE5 + V _d6 ... (4) Therefore, ΔV _L = V _CE5 + V _d6 -V _BE9 × (1 + R ₇ / R ₈ ) ... (1) 5) On the other hand, in the device of the present invention, the resistance values of the resistors 37 and 38 are respectively set to R
As _{37, R 38, V L0 =} V 1 ... (6) V L1 = V 2 = V 1 × (1 + R 37 / R 38) ... (7) _{Therefore, ΔV L = V 1 × (} R 37 / R 38) ... (8) In the conventional device, the difference voltage ΔV _L is a voltage having a large temperature-dependent fluctuation determined by V _CE , V _d , and V _BE , but in the device of the present embodiment, as shown in the equation (8), A stable voltage determined only by the value is obtained.

The embodiment described above is an embodiment of the present invention, and various modifications of the circuit configuration are conceivable. For example, the base current control circuit 34 shown in FIG. 2, the power supply voltage V _CC from the control power supply line 43 and insert the voltage regulator for stabilizing, it is desirable to further stabilize the voltage V _L of the L terminal 4. Alternatively, the lamp driving transistor 5 may be changed to a PNP transistor, and the resistor 53 may be omitted to provide a circuit configuration that is resistant to fluctuations in the power supply voltage V _CC .

Conversely, as shown in FIG.
The input stage is constituted by a differential amplifier constituted by an NPN transistor 61 and the output stage is constituted by a PNP transistor 62, whereby the resistor 53 can be omitted and the circuit configuration can be simplified.

Further, in the base current control circuit 34 shown in FIG. 4, a capacitor 65 is added to the output stage 62 so that the voltage V _L of the L terminal 4 and the second
It is a circuit configuration providing the base of the lamp driving transistor 5 by the setting current mirror circuit a current which is determined by the difference voltage between the voltage V _1. In this circuit, the second can be matched to the set voltage V ₂ stable voltage V _L of the L terminal 4, it is possible to further stabilize the operation of the lamp driving transistor 5. This circuit can be easily integrated into an IC by connecting the capacitor 65 externally.

FIG. 5 is a circuit diagram showing an embodiment in which a differential amplifier is not used as a base current control circuit.

The voltage V _L L terminal 4 by the resistors 7 and 8 divides connected to the base of the input detecting transistor 9, the circuit arrangement for turning the PNP transistor 10 by the conduction of the on detection transistor 9, in FIG. 6 This is the same as the conventional device shown. In this embodiment, the base current control circuit 70, the base current of the lamp driving transistor 5 is controlled according to the voltage V _L of the L terminal 4. In the base current control circuit 70, the input stage is configured by an amplifier circuit including a resistor 71 and NPN transistors 72 and 73, and the output stage is configured by an amplifier circuit including PNP transistors 74 and 75. The input stage resistor 71 is connected to the L terminal 4 and the output is connected to the base of the lamp driving transistor 5.

In this circuit configuration, the first set voltage VV ₁ for turning the PNP transistor 10 is expressed by the following equation.

VV ₁ = V _BE9 × (1 + R ₇ / R ₈ ) (9) This equation is the same as the equation (3). On the other hand, the second set voltage VV ₂ is expressed by the following equation.

_{VV 2 = V BE72 + I R71} × R 71 ... (10) where V _BE72 is the base-emitter voltage of the transistor 72 of the first stage, the current I _R71 is flowing through the resistor 71, R ₇₁ is the resistance of resistor 71 . Therefore, it is possible to set so that VV ₂ > VV ₁ by appropriately selecting each constant.
The diode 6 can be omitted.

[Effects of the Invention] The present invention is configured as described above and includes a circuit for controlling the base current of the lamp driving transistor, and thus has the following effects.

The diode which is a power element can be dispensed with even though it is a device for detecting the turning on of the key switch by the L terminal. For this reason, heat generation can be suppressed, the mounting space can be reduced, and furthermore, IC integration is facilitated.

Further, by employing a circuit which is not strongly affected by temperature as the set voltage applying circuit, stable operation can be performed without malfunction due to leak current even in a high temperature environment.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a circuit diagram showing a charge display device of a voltage regulator, FIG. 2 is a circuit diagram showing a base current control circuit, and FIGS. FIG. 4 is a circuit diagram showing second and third embodiments of the base current control circuit, FIG. 5 is a circuit diagram showing a fourth embodiment, and FIG. 6 is a circuit diagram showing a conventional charge display device. It is. 1 ... battery, 2 ... key switch, 3 ... charge lamp (charge indicator light), 4 ... L terminal, 5 ... lamp driving transistor, 6 ... diode, 10 ... PNP transistor, 11 ... Excitation current control circuit, 33 ... closing detection circuit, 34 ... base current control circuit, 36, 37, 38 ... resistance (setting voltage application circuit).

Claims (1)

(57) [Claims] A circuit in which a key switch, a charge indicator, and a transistor are connected in series from the positive electrode to the negative electrode of the battery is provided. The circuit has a function of lighting the charge indicator by the conduction of the transistor. A charge display device for a vehicle voltage regulator that detects the turning on of a key switch based on the voltage of a connection point (hereinafter, referred to as an L terminal) between the transistor and a transistor, and excites a generator. A setting voltage providing circuit for respectively providing a higher second setting voltage; a closing detection circuit for detecting a voltage of the L terminal and outputting a detection signal when the voltage exceeds the first setting voltage; An exciting current control circuit for starting excitation of the generator by means of the transistor; and detecting a voltage at the L terminal and increasing or decreasing a base current according to a difference between the second set voltage and the transistor. And a base current control circuit that can be supplied to the vehicle.